Cannabinoids for control of chemotherapy induced nausea and vomiting: quantitative systematic review

Objective To quantify the antiemetic efficacy and adverse effects of cannab is used for sickness induced by chemotherapy. Design Systematic review Data sources Systematic search (Medline, Embase, Cochrane library bibliogra phies), any language, to August 2000. Studies 30 randomised comparisons of cannabis with placebo or antiemetics f rom which dichotomous data on efficacy and harm were available (1366 patien ts). Oral nabilone, oral dronabind (tetrahydrocannabinol), and intramuscula r levonantradol were tested. No cannabis was smoked. Follow up lasted 24 ho urs. Results Cannabinoids were more effective antiemetics than prochlorperazine, metoclopramide, chlorpromazine, thiethylperazine, haloperidol, domperidone , or alizapride: relative risk 1.38 (95% confidence interval 1.18 to 1.62), number needed to treat 6 for complete control of nausea; 1.28 (1.08 to 1.5 1), NNT 8 for complete control of vomiting: Cannabinoids were not more effe ctive in patients receiving very low or very high emetogenic chemotherapy. In crossover trials, patients preferred cannabinoids for future chemotherap y cycles: 2.39 (2.05 to 2.78), NNT 3. Some potentially beneficial side effe cts occurred more often with cannabinoids: "high" 10.6 (6.86 to 16.5), NNT 3; sedation or drowsiness 1.66 (1.46 to 1.89), NNT 5; euphoria 12.5 (3.00 t o 52.1), NNT 7. Harmful side effects also occurred more often with cannabin oids: dizziness 2.98 (2.31 to 3.83), NNT 3; dysphoria or depression 8.06 (3 .35 to 19.2), NNT 8; hallucinations 6.10 (2.41 to 15.4), NNT 17; paranoia 8 .58 (6.35 to 11.5), NNT 20; and arterial hypotension 2.23 (1.75 to 2.83),NN T 7. Patients given cannabinoids were more likely to withdraw due to side e ffects 4.67 (3.07 to 5.09), NNT 11. Conclusions In selected patients, the cannabinoids tested in these trials m ay be useful as mood enhancing adjuvants for controlling chemotherapy relat ed sickness. Potentially serious adverse effects, even when taken short ter m orally or intramuscularly, are likely to limit their widespread use.